Sanne de Bruin

160 Chapter 6 Free fatty acids in PAGGGM RBCs Palmitic and stearic acid were significantly higher in PAGGGMRBCs prior to transfusion, while in the restored cells no difference was found. Palmitoleic acid and oleic acid, were similar in the PAGGGM and SAGM RBCs. Lineolic acid was similar in PAGGGM and SAGM RBCs prior to transfusion, while 1 day after transfusion lower levels were found in the PAGGGM RBCs. Arachidonic acid showed increased levels in PAGGGM RBCs prior to transfusion. However, there were no differences after transfusion. Glycolysis metabolism 35 days after SAGM storage After 35 days of storage glycolysis activity is decreased (Figure 5). This was indicated by complete depletion of ATP levels, decreased DPG levels and increased AMP levels compared to 2 days stored RBCs. In addition, the levels of several glycolysis metabolites (hexose phosphate, fructose-1,6-biphosphate, 2/3-phosphoglycerate, phosphoenolpy- ruvate and pyruvate) were decreased in the 35 days SAGM stored RBCs compared to 2 days SAGM stored RBCs. Directly after transfusion, glycolysis activity recovered, illustrated by immediate recov- ery of ATP levels. Furthermore, AMP and ADP levels were similar after transfusion. DPG and phosphoenolpyruvate remained higher in 2 days stored RBCs until 10 minutes after transfusion, despite inter-donor heterogeneity. Redox metabolism No evident effect of storage time was found in G6PD activity, which was similar in the 2- and 35 days stored RBCs (Figure 6). Only 6-phosphogluconate levels were significantly higher in 2 days stored RBCs prior to transfusion. However, this normalized directly after transfusion. Ribose-phosphate was higher in 2 days stored RBCs 6 hours after transfu- sion, while prior to transfusion no effect was observed. In addition, no differences were found in sedoheptulose levels (Figure 7). We did observe an increased breakdown of GSH and GSSG in the 35 days stored RBCs. Oxoproline levels were significantly higher in 35 days stored RBCs with similar levels of GSH but lower levels of GSSG, indicating an increased breakdown of GSH. After trans- fusion, no differences in these levels were found in the cells that recovered.